Integrated circuits are typically formed by processing several semiconductor wafers as a group or “lot” through a series of wafer fabrication process tools (hereafter, “process tools”). Each process tool typically performs a single wafer fabrication operation upon the semiconductor wafers. The integrated circuits formed in this manner are substantially identical to one another. Following wafer fabrication, the integrated circuits are typically subjected to functional testing, and then separated to form individual integrated circuits called “chips” or “die.” Fully functional die are typically packaged and sold as individual units.
During operation of a process tool, one or more operating conditions are established within the process tool, typically dependent upon input (e.g., control signals) from a centralized Manufacturing Execution System (MES). An Automated Material Handling System (AMHS) is programmed to move the wafers to the needed process tools in the specified sequence to produce the finished chips.
The MES may use standard factory automation methods for semiconductor manufacturing, such as the Advanced Process Control (APC) Framework family of specifications and process tool equipment communication standard II (SECS II), which are publicly available from SEMI (The Semiconductor Equipment and Materials Institute, commonly known as SEMI, is an organization headquartered in San Jose, Calif., that publishes various specifications for the semiconductor industry). These methods are well known in the industry, and are disclosed in U.S. Pat. No. 6,907,306 (entitled “Process tool throughput monitoring system and method”) which is herein incorporated by reference in its entirety.
With many process tools, each having possibly hundreds of individual parameters, the task of monitoring a semiconductor manufacturing line can be challenging. To be cost effective, delays due to faulty (or out-of-tolerance) equipment must be minimized. Quick detection of such problems is paramount to minimizing this delay. Therefore, what is needed is an improved system and method for monitoring a semiconductor manufacturing process.